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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (March 5, 2012) is 4434 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'G.FLEXIGRID' is mentioned on line 99, but not defined Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 CCAMP Working Group D. Ceccarelli 3 Internet-Draft G. Bottari 4 Intended status: Informational Ericsson 5 Expires: September 6, 2012 N. Sambo 6 Scuola Superiore S.Anna 7 F. Cugini 8 C.N.I.T. 9 F. Zhang 10 Huawei Technologies 11 R. Casellas 12 CTTC 13 March 5, 2012 15 Guard Bands requirements for GMPLS controlled optical networks 16 draft-cbcs-ccamp-sson-guard-bands-reqs-00 18 Abstract 20 The continuous increase of flexibility and bit rate in optical 21 networks has higher and higher impacts on inter-channel effects (e.g. 22 Cross-phase modulations). This effect leads to the introduction of 23 Guard Bands between adjacent light paths in order to reduce the 24 inter-channel detrimental effects. 26 This document provides requirements for the devolpment of protocol 27 extensions to support Generalized Multi-Protocol Label Switching 28 (GMPLS) and Path Computation Element (PCE) management of Guard Bands. 30 Status of this Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on September 6, 2012. 47 Copyright Notice 48 Copyright (c) 2012 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 65 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 3. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 4. Guard Band definition . . . . . . . . . . . . . . . . . . . . . 4 68 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 5 69 5.1. PCE Requirements . . . . . . . . . . . . . . . . . . . . . 5 70 5.2. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . 7 71 5.3. GMPLS Requirements . . . . . . . . . . . . . . . . . . . . 7 72 5.3.1. OSPF-TERequirements . . . . . . . . . . . . . . . . . . 7 73 5.3.2. RSVP-TE Requirements . . . . . . . . . . . . . . . . . 7 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 75 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 76 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 8 77 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 78 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 79 10.1. Normative References . . . . . . . . . . . . . . . . . . . 8 80 10.2. Informative References . . . . . . . . . . . . . . . . . . 9 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 83 1. Introduction 85 Given the advancement of optical transmission technology, optical 86 channels may use thinner granularity of the spectrum, which are 87 configurable depending on the modulation format and bit-rate 88 [G.FLEXIGRID]. Thus, thanks to this flexibility, the capacity of 89 optical networks is strongly increasing. However, the spacing 90 between channels may be limited by the inter-channel effects (e.g, 91 cross-phase modulation - XPM) which can lead to a bit error rate 92 increase. Typically, as the case of XPM or cross-talk, the larger 93 the spectral distance among interfering signals, the less detrimental 94 the effect. Thus, a guard band (i.e., a spectral distance such that 95 detrimental effects are mitigated) may be considered to counteract 96 inter-channel detrimental effects [sambo-jlt]. 98 Guard Bands (GB) may be required in either fixed- [RFC6163] or 99 flexible-grid networks [G.694.1v1] [G.FLEXIGRID]. As an example, in 100 fixed-grid networks, high-speed signals (100Gbit/s and beyond) may be 101 deployed together with low-speed signals (10Gb/s). In such a 102 scenario, high-speed signals utilizing phase-modulated formats (e.g., 103 dual polarization quadrature phase shift keying - DP-QPSK - 100Gb/s) 104 suffer from XPM induced by low-speed signals, exploiting intensity 105 modulation (e.g. on off keying - OOK - 10Gb/s). Thus, GB may be used 106 to avoid problems of XPM between low- and high-speed signals. 107 Similarly, in flex-grid networks, high-speed signals may exploit 108 quadrature amplitude modulation (QAM), which experience both 109 intensity and phase modulation. Also in such a scenario, XPM may be 110 very detrimental. 112 The value of a guard band may depend on physical properties of the 113 traversed links and on the bit rate and modulation format of the 114 interfering signals. Given two interfering signals, inter-channel 115 effects among the two signals are counteracted if they are separated 116 by GB. This document describes the requirements of PCE and GMPLS 117 control to account for guard bands. 119 1.1. Terminology 121 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 122 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 123 document are to be interpreted as described in [RFC2119]. 125 2. Definitions 127 Demeaning LSP: an LSP which induces a detrimental effect on 128 another LPS 129 Degraded LSP: an LSP which may be degraded by inter-channel 130 effects induced by a demeaning GB: guard band 132 Working LSP: an active LSP 134 RSA: routing and spectrum assignment 136 IV: impairment validated (e.g., a route is impairment validated if 137 its bit error rate is acceptable for any channel) 139 3. Scenarios 141 Fixed-grid network is here assumed as a particular case of flex-grid 142 network, thus hereafter only the case of flex-grid networks will be 143 treated. Similarly, RWA is assumed as a particular case of RSA and 144 only RSA will be treated. The following PCE scenarios are considered 145 [draft-flexible]: 147 - IV and RSA PCE : From a GB point of view there is no difference 148 between IV+RSA and IV&RSA, so a general IV+RSA case will be 149 considered. In this case the PCE provides the ingress node with 150 an impairment-validated route and a set of frequency slots. 152 - IV PCE: PCE provides ingress node with an impairment-validated 153 route. Then, slot assignment is distributed and performed by the 154 egress node which may rely on collecting link status through the 155 signaling protocol (RSVP-TE). 157 - IV Candidate path PCE: PCE provides ingress node with a set of 158 candidate routes (i.e., a set of impairment-validated routes). 159 Then, a route is selected by the ingress node. Slot assignment is 160 distributed and performed by the egress node through the signaling 161 protocol (RSVP-TE). 163 4. Guard Band definition 165 GB is defined as the minimum frequency range which separates two 166 contiguous signals, S1 at bit rate B1 and modulation format M1 and S2 167 at a bit rate B2 and modulation format M2, such that detrimental 168 effects are negligible. 170 S1(B1;M1) S2(B2;M2) 171 ------------- ------------------- 172 | | | | 173 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 174 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 175 ------------- ------------------- 176 <---> 177 GB 179 Figure 1: Guard Band 181 Assuming fixed-grid networks, a number of channels (e.g. of a grid 182 spacing of 50 GHz), instead of a number of slots would be considered 183 for GB. 185 The computation of GB may require the knowledge of: 187 a. bit rate B and modulation format M of the interfering signals 189 b. the power P values of the signals at each span. In order to 190 limit the stored and exchanged information, an unique value of P 191 (worst-case scenario) may be considered for the demeaning LSP: 192 i.e., the maximum value P experienced by an LSP of type (B2,M2). 193 Similarly, an unique value P (worst-case scenario) may be 194 considered for the degraded LSP: the minimum value P experienced 195 by an LSP of type (B1,M1). 197 c. Fiber parameters: e.g. fiber attenuation, dispersion 198 parameter, and fiber nonlinear Kerr coefficient 200 Bit rate and modulation format should be mandatory information for GB 201 computation (e.g., PCE may select the value of GB from a stored set 202 of GB values, each one associated to a bit rate and modulation format 203 pair), thus treated in the rest of the document. 205 5. Requirements 207 5.1. PCE Requirements 209 - IV+RSA PCE: given an LSP request, by exploiting a TED, PCE may 210 account for GB in the IV+RWA (or IV&RSA) process, if needed. In 211 the case of: 213 + Stateful PCE: PCE has a TED (in simple terms as disseminated 214 by OSPF-TE) plus an LSP-DB which are the active LSPs state. 215 (e.g., the route and the slot used by a working LSP). In order 216 to identify the required GB, the TED plus the LSP-DB exploited 217 by the PCE should be extended to store the following 218 information: 220 ++ Bit rate B of any working LSP in the network 222 ++ Modulation format M of any working LSP in the network 224 ++ Allocated central frequency and slot width for any active 225 LSP in the network. 227 + Stateless PCE: PCE exploits a TED which includes per-link 228 information regarding the usage of the optical spectrum 229 resource (e.g., Available Frequency Ranges). If the PCE 230 obtains the TED via e.g. OSPF-TE this may also add additional 231 requirements to OSPF-TE as detailed later on. In order to 232 identify the required GB, the TED exploited by the PCE should 233 be extended to store the set of required information. An 234 example of such pieces of information could be: 236 ++ Used frequency slots 238 ++ Bit rate B associated to any frequency slot in use 240 ++ Modulation format M associated to any frequency slot in 241 use 243 - IV PCE: given an LSP request, PCE provides the ingress node with 244 an impairment validated route. Then, wavelength or the slot 245 assignment is distributed, e.g. performed through a signaling 246 protocol (RSVP-TE). In this case, PCE should inform the ingress 247 node about the requirements of GB to separate the given LSP from 248 other LSPs of specific bit rate B and modulation format M. Thus, 249 PCEP and RSVP-TE may require extensions to account for GB. 251 - IV Candidate path PCE: given an LSP request, PCE provides the 252 ingress node with a set of impairment validated routes. A route 253 is selected by the ingress node. Then, wavelength or the slot 254 assignment is distributed, e.g. performed through a signaling 255 protocol (RSVP-TE). In this case, PCE should inform, for each 256 candidate route, the ingress node about the requirements of GB to 257 separate the given LSP from other LSPs of specific bit rate B and 258 modulation format M. Thus, PCEP and RSVP-TE may require extensions 259 to account for GB. 261 5.2. PCEP Requirements 263 - IV&RSA PCE: in this case, no extensions for GB are required by 264 PCEP because PCEP client (e.g., the ingress node) does not require 265 to know GB information 267 - IV PCE: in this case, an extension may be needed in the PCEP 268 Path Computation Reply message to inform the ingress node about 269 required GBs along the route. Then, GB information should be 270 considered in the routing and slot assignment. 272 - IV candidate path PCE: in this case, an extension may be needed 273 in the PCEP Path Computation Reply message to inform the ingress 274 node, for any candidate route, about required GBs along the 275 candidate routes. Then, GB information should be considered in 276 the routing and slot assignment. 278 5.3. GMPLS Requirements 280 5.3.1. OSPF-TERequirements 282 - Stateful PCE: the LSP-DB is not filled through OSPF-TE, thus no 283 OSPF-TE extension is required. 285 - Stateless PCE: the TED may be filled through OSPF-TE, thus 286 OSPF-TE extensions may be required to carry used frequency slot 287 information, such as the associated bit-rate B and modulation 288 format M. 290 5.3.2. RSVP-TE Requirements 292 If the PCE only provides the ingress node with a route (IV PCE and IV 293 candidate path PCE), the slot assignment is performed at the egress 294 node. To this aim, RSVP-TE Path message gathers frequency range slot 295 availability information along the route. 297 - IV&RSA PCE: no extensions for GB are required by RSVP-TE 299 - IV PCE: extensions to RSVP-TE may be required to enable 300 distributed RSA process which accounts for GB. In particular, 301 extensions to RSVP-TE may be required to identify the frequency 302 spectrum along the route that should be not selected because of 303 GB. 305 - IV candidate path PCE: extensions to RSVP-TE may be required to 306 enable distributed RSA process which accounts for GB. In 307 particular, extensions to RSVP-TE may be required to identify 308 frequency spectrum along the route that should be not selected 309 because of GB. 311 6. Security Considerations 313 TBD 315 7. IANA Considerations 317 TBD 319 8. Contributors 321 Fabio Cavaliere, Ericsson 323 Email: fabio.cavalier@ericsson.com 325 Paola Iovanna, Ericsson 327 Email: paola.iovanna@ericsson.com 329 Piero Castoldi, Scuola Superiore S.Anna 331 EMail: castoldi@sssup.it 333 9. Acknowledgements 335 10. References 337 10.1. Normative References 339 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 340 Requirement Levels", BCP 14, RFC 2119, March 1997. 342 [RFC6163] Lee, Y., Bernstein, G., and W. Imajuku, "Framework for 343 GMPLS and Path Computation Element (PCE) Control of 344 Wavelength Switched Optical Networks (WSONs)", RFC 6163, 345 April 2011. 347 10.2. Informative References 349 [G.694.1v1] 350 ITU-T, "Spectral grids for WDM applications: DWDM 351 frequency grid", G.694.1 Recommendation (v1), 352 December 2011. 354 [draft-flexible] 355 F.Zhang, Y.Lee, O. Gonzales de Dios, R.Casellas, 356 D.Ceccarelli, "Framework for GMPLS Control of Spectrum 357 Switched Optical Networks, work in progress 358 draft-zhang-ccamp-sson-framework-00", March 2011. 360 [sambo-jlt] 361 Sambo, N.; Secondini, M.; Cugini, F.; Bottari, G.; 362 Iovanna, P.; Cavaliere, F.; Castoldi, P, "Modeling and 363 Distributed Provisioning in 10-40-100-Gb/s Multirate 364 Wavelength Switched Optical Networks, Lightwave 365 Technology, Journal of , vol.29, no.9, pp.1248-1257", 366 May 2011. 368 Authors' Addresses 370 Daniele Ceccarelli 371 Ericsson 372 Via A. Negrone 1/A 373 Genova - Sestri Ponente 374 Italy 376 Email: daniele.ceccarelli@ericsson.com 378 Giulio Bottari 379 Ericsson 380 Via G.Moruzzi, 1 381 Pisa 382 Italy 384 Email: giulio.bottari@ericsson.com 385 Nicola Sambo 386 Scuola Superiore S.Anna 387 Via G.Moruzzi, 1 388 Pisa 389 Italy 391 Email: nicola.sambo@sssup.it 393 Cugini 394 C.N.I.T. 395 Via G.Moruzzi, 1 396 Pisa 397 Italy 399 Email: filippo.cugini@cnit.it 401 Fatai Zhang 402 Huawei Technologies 403 F3-5-B R&D Center, Huawei Base 404 Shenzhen 518129 P.R.China Bantian, Longgang District 405 Phone: +86-755-28972912 407 Email: zhangfatai@huawei.com 409 Ramos Casellas 410 CTTC 411 Av. Carl Friedrich Gauss, 7 412 Castelldefels 413 Spain 415 Email: ramon.casellas@cttc.es